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This invention relates generally to methods and apparatus for directing the light produced by a plurality of light sources to a plurality of light sinks and more specifically to methods and apparatus for connecting arrays of light sources to arrays of light sinks.
The tremendous information-carrying capacity of light beams is stimulating the development of the hardware building blocks for communication systems of a variety of types. A variety of devices are presently available for the generation and detection of light for communication purposes. Moreover, these devices tend to be small, and the available manufacturing technology permits these devices to be fabricated precisely and economically into large-scale arrays.
What is not so readily available are the means for economically interconnecting arrays of these devices. The interconnection means of choice at the present time, particularly for long distances, is the fiber-optic cable consisting of a plurality of optical fibers held together by a flexible matrix. After decades of development, the connection of fiber-optic cables to optical devices remains a costly labor-intensive exercise.
It is becoming increasingly desirable to connect optical devices to other optical devices on the same printed-circuit board. For this purpose, guiding light beams from one array of optical devices to another array using waveguides have been explored during the past decade. The idea is to provide a waveguide between each pair of devices to be connected. Short-length fiber-optic cables are one possible way in which arrays of optical devices can be connected together.
Rather than using ready-made short-length fiber-optic cables to connect optical devices on a printed-circuit board, one might use custom-fabricated arrays of optical waveguides on suitable substrates. The manufacturing process for optical waveguide arrays is similar, at least in some respects, to the manufacturing process for integrated circuits. However, even though the integrated-circuit manufacturing process is complex, it is also cost-effective when amortized over millions of integrated circuits. Optical connectors based on arrays of optical waveguides are unlikely to have the market potential of commodity-type integrated circuits and will, for this reason, be significantly less cost-effective than the typical integrated circuit.
There is a continuing need for optical connectors that are as cost-effective as printed-circuit boards are for connecting arrays of electronic devices.
The invention is a method and apparatus for transmitting the light from one or more transmitting arrays of optical devices to one or more receiving arrays of optical devices where each optical device in a transmitting array transmits an initially diverging light beam to a single optical device in a receiving array. Each optical device in a receiving array receives a converging light beam from a single optical device in a transmitting array. The method consists of imaging the optical devices in one or more transmitting arrays on the optical devices in one or more receiving arrays. The light rays from each optical device in a transmitting array are superimposed on the light rays from the other optical devices in the transmitting array while traversing a common volume.